Self-stripping terminal clamp



A ril 28, 1970 c. E. GUTSHALL 3,509,517

SELF-STRIPPING TERMINAL CLAMP Filed Feb. 15, 1968 50 BY ZMZU His Arrjys United States Patent 3,509,517 Patented Apr. 28, 1970 3,509,517 SELF-STRIPPING TERMINAL CLAMP Charles Edward Gutshall, Roselle, IlL, assignor to Illinois Tool Works Inc., Chicago, 11]., a corporation of Delaware Filed Feb. 15, 1968, Ser. No. 705,674 Int. Cl. H01r 9/08 US. Cl. 339-98 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an electrical connector including a screw element adapted to coact with the workpart, a U-shaped saddle clip, and a novel form of clamping element associated with the clip and adapted to cooperate with the aforementioned screw to both scrapingly and bitingly engage a conductor with which it is associated to assure a self-stripping of the insulation or oxide coating which may be initially associated with the conductor.

This invention relates to a electrical connector or terminal clamp for removably securing the end of a conductor to a workpiece, and more specifically, it relates to these types of connectors or clamps which are adapted to be utilized with terminal plugs, buss bars, circuit breakers, and the like.

In typical terminal block assemblies there is provided a plurality of elongated terminal blocks at pre-determined distances from one another, each being adapted to receive at least one conductor element which is connected thereto by a terminal clamp or electrical connector. If a pre-determined distance between terminal blocks is not maintained, the air gap between adjacent terminals, under certain conditions, may readily carr a current, and under such circumstances cause an undesirable electrical arc between adjacent terminals.

The problem is many times further complicated by the fact that it is sometimes necessary to clamp a plurality of conductors to a terminal block by the same terminal clamp. In such instances the terminal clamp must be able to accommodate and efiiciently clamp different sized conductors without requiring greater separating distances between adjacent terminal blocks. The prior art discloses various approaches which have been tried such as the device shown in the patent to J. E. Carlson, 2,161,246. This device is mounted between shoulder portions, restrained from rotation relative to said shoulders and presents a pair of passageways to accept conductors of the same or different sizes. The device accomplishes a pressure contact by surfaces and fails to disclose or define a device which will accomplish the biting engagement of the clamping element of the conductors with which it is associated, or to accomplish self-stripping of insulation or oxide coating which may be associated with the conductor to assure an intimate and satisfactory electrical connection.

Accordingly, it is an object of the present invention to provide a new and improved terminal clamp or electrical connector which provides for efficient pressure clamping of one or more electrical conductors to terminal blocks, while at the same time providing a biting engagement of, and a stripping action relative to, the conductor and the insulation or coatings of the conductor associated therewith.

Another object of the present invention is to provide a new and improved terminal clamp which may, under required circumstances, be provided with extra gripping elements which likewise strip the insulation from and thereafter bitingly engage the conductor in the same fashion in which the primary elements of the clamping blade accomplish this task.

Another object of the present invention is to provide a terminal clamp of the type described wherein additional means may be provided, where appropriate, which will prevent complete flattening of the clamping plate and at the same time provide additional clamping force to the conductor to prevent its inadvertent movement relative to the clamping plate.

Other objects of the present invention will be apparent along with the advantages of the structure, when taken into consideration relative to the following descriptions and with the accompanying drawings, wherein:

FIG. 1 of the drawings is a perspective view of the three piece end terminal clamp assembly contemplating the invention. The view shows the underside of the fastener assembly.

FIG. 2 is a perspective view of the assembly with a portion of the U-shaped body shown in dashed lines to accurately permit portrayal of the new and improved clamping element constituting an important part of this invention. 1

FIG. 3 shows another embodiment of a clamping element, differing from the element shown in FIG. 2, which permits additional adjustability for clamping conductors of varying cross-sectional sizes simultaneously together with special gripping elements that can be provided to facilitate the stripping of insulation or coating from and subsequent electrical contact of the conductor with which it is associated.

FIG. 4 shows still another embodiment of a clamping element which includes the basic wire stripping and impinging mechanism, but also has an additional gripping and clamping element to afford additional utility in its end use.

FIG. 5 is a cross-sectional view of the assembly shown in FIG. 1 with the terminal clamp associated with a conductor. It clearly portrays the stripping and impinging action accomplished by the structure involved in the instant invention.

Referring now to the drawings, it will be noted that the invention, as portrayed in FIG. 1, consists of a rotary threaded fastener 10 having mounted thereon a U-shaped saddle clamp 12 including an intermediate or bight portion 13 which is provided with an aperture 15 (not shown) normally mounted in such a fashion that there is sufficient clearance because of the predetermined size of the aperture 15 relative to the diameter of the screw to permit lateral movement and tipping movement of the saddle clip 12 to permit it to conform to conditions which must be met with conductors of various sizes and configurations and manufacturing inaccuracies found in terminal blocks or buss bars 50 as shown in FIG. 5 of the drawings. The third element of the assembly, and a most vital one in the new combination contemplated by thi invention, is the clamping element 14. This element can be provided with an aperture smaller than the crest diameter of the threads of the screw 10 in which case the clamping element holds the saddle clip in adjacent relation to the screw head 17 so that as the screw is rotated relative to the workpart with which it is associated the assembly i either jacked up or lowered gradually relative to the workpart. Alternatively, the aperture in the clamp element 14 can be of such a size that it is greater than the crest diameter of the screw threads, in which case the assembly is not preassembled but consists of three distinct elements which are associated with other just prior to usage.

In FIG. 2, the assembly is shown in a perspective top view with a portion of the saddle clip 12 broken away in order that the area of the clamping element 14 be clearly pictured from the standpoint of being longitudinally arched relative to the bight portion 13 of the saddle clip. In this view the details of the clamping element can best be seen and understood. Clamping element 14 has a pair of biting edges 19 provided at spaced positions, and, as shown, at the terminal ends of the clamping element. These edges traverse the passageway afforded by the side flanges 21 of the saddle clip and, as shown in FIG. 2, are held in readiness for conductors to be placed beneath them for clamping against a workpart 50. The workpart 50 is normally of a dimension somewhat less than the space between the saddle clip flanges 21 and provided with a threaded aperture. As the rotary fastener is mounted in the threaded aperture and the side flanges embrace the side edges or margins of the workpiece 50 a passageway is provided into which a conductor or several conductors may be positioned. A the screw is rotated into the threaded aperture the clamping element is brought into contact with the conductor or conductors 20 (see FIG. and the biting edges 19 begin to impinge upon and subsequently pierce any coating on the conductor such as electrical insulation, oxide coating, etc. Further, pressure applied to the clamping element causes further embedment and a lengthening of the clamping element as its configuration is transformed from an arch having a predetermined radius of curvature to a flattened position with lesser curvature. This lengthening of the clamping element 14 as it is compressed affords the scrap ing and skiving action which are so vital to the spirit of this invention. Devices made in accordance with the invention shown in the drawings have, after bitingly engaging and coming to a scraping halt on the conductor body afforded excellent electrical connection both initially and with time because of the spring action which continues to exist in the pressure connection afforded by this assembly.

In FIG. 3, of the drawings I show a modified form of the clamping element 14 which I have designated 14A. Two features are specifically described which enhance the utility of the clamping element in certain situations. The first situation relates to affording a pair of slots 23 at opposite ends of the clamping element to present a substantially bifurcated clamping body which is turn affords four biting edges 19, all independently flexible of each other. It will be readily understood by the reader that this assures independent biting action of four elements relative to two or more conductors that may be placed beneath the clamping element. Secondly, another feature which is clearly portrayed in FIG. 3 is the independent biting fingers 16 which may be provided along the side margins of the longitudinally arched body to add a plurality of additional biting edges to bite through and clampingly impinge upon the conductor body. This affords additional assurance of sufficient electrical contact of the clamping element with the conductor and at the same time adds additional engagement to prevent longitudinal forces applied to the conductor in an effort to remove it by inadvertence or otherwise.

In FIG. 4, additional gripping is provided on a clamping element 143 by the provision of dimples 18 which are coined into the body and cause projections to extend into the concavity provided by the longitudinally arched body. It will be readily understood that as the clamping element is deflected or compressed that these elements will grip- 4 pingly engage the insulation on a conductor to add a strain relief to a conductor or conductors grippingly engaged by the element against a workpart.

Lastly, in FIG. 5, I have tried to portray a clamping element of the type as shown in FIG. 4, including the gripping elements 18 to show the operation of the assembly. It should be noted, in viewing the conductor 50 that the insulation 24 has been stripped back in the vicinity of the biting edges 19 and that these edges are embedded into the wire and have skived conductor material outwardly due to the elongation of the arched body as it is compressed. The clamping element 18 assures firm engagement of the insulation and additionally acts to prevent collapse of the clamping element if undue pressures are applied in an effort to obtain the desired electrical connection.

While the preferred embodiments of the present invention have been shown and described herein, it is obvious that many structural details may be changed without departing from the spirit of the invention, wherein what I claim is:

1. An electrical connector for removably securing the terminal end of at least one complementary conductor to an apertured work part comprising a rotary threaded fastener, a U-shaped clip means associated with said fastener and including down-turned, oppositely disposed flanges at opposite sides of an apertured bight portion which accepts said rotary threaded fastener, the length and spacing of said down-turned flanges on the bight portion of said U-shaped clip means permitting the accommodation of said apertured work part therewithin, a spring clamping means positioned intermediate said clip means and said aperture work part and being nestably received between the down-tumed flanges of said clip means, said spring clamping means having an opening aligned with the aperture of said clip means to accept said rotary threaded fastener, said clamping means being longitudinally arched to present at opposite free ends a pair of spaced biting edges which traverse the passageway defined by the aforesaid down-turned flanges, said biting edges being adapted on impingement upon an electrical conductor to bitingly engage the complementary conductor as the clamping means is collapsed incident to pressure by the rotary fastener whereby said clamping means will move longitudinally along the conductor to scrape the conductor and thus assure intimate electrical contact relative to said work part, said clamping means further being provided with a plurality of sheared fingers presenting secondray biting edges spaced inwardly from said free ends and located in the concavity of the arched clamping means to thereby afford additional biting edges to pierce the conductor insulation and lbitingly engage the conductor to afford a suitable electrical connection.

2. An electrical connector for removably securing the terminal end of at least one complementary conductor to an apertured work part comprising a rotary threaded fastener, a U-shaped clip means associated with said fastener and including down-turned, oppositely disposed flanges at opposite ends of an apertured bight portion which accepts said rotary threaded fastener, the length and spacing of said down-turned flanges on the bight portion of said U-shaped clip means permitting the accommodation of said apertured work part therewithin, and spring clamping means positioned intermediate said clip means and said apertured work part and being nestably received between the down-turned flanges of said clip means, said spring clamping means having an opening aligned with the aperture of said clip means to accept said rotary threaded fastener, said clamping means being longitudinally arched to present at opposite free ends a pair of spaced biting edges which traverse the passageway defined by the aforesaid down-turned flanges, said biting edges being adapted on impingement upon an electrical conductor to bitingly engage the complementary conduc- 5 6 tor as the clamping means is collapsed incident to pres- References Cited sure bylthe rotary lflastelner wlflereby Said clamping meakrlrs UNITED STATES PATENTS moves ongitudina y a ong t e con uctor to scrape t e conductor and thus assures intimate electrical contact relg iggf ative to said work part, said clamping means being par- 5 3083348 3/1963 g 95 tially severed at each of its free end margins inwardly 3238495 3/1966 Lanius 5 and in a longitudinal direction to provide a plurality of 3:3O9Z646 3/1967 g'II": 339 98 independent flexible biting edges at each end of the clamping means to facilitate biting engagement with each of a A I A CHAMPION, Primary Examiner f d t h t d iagssgcigtzr uc 01s w1th WhlCh t e elec rlcal con uctor 10 J H. MCGLYNN Assistant Examiner 

